Modern buildings are often equipped with controllable window treatment, such as motorized shades or blinds, to control the amount of sunlight entering the building through openings, typically through windows. Moreover, modern buildings are often also equipped with controllable electric lights permitting to control the light level of individual or groups of electric lights fixtures. The light level control is typically achieved by dimmers. Generally it is beneficial to use the daylight as much as possible. For the occupants of the building, illumination by daylight normally leads to increased well-being. From an environmental as well as cost perspective, optimal use of daylight to illuminate the interior of a building may reduce the energy consumption of the building due to reduced electric lighting requirements. Moreover, optimal control may further lead to reduced heating and cooling requirements as well. In many situations, the window treatment and the electric lights are controlled manually and/or independently from each other, leading to sub-optimal use of the daylight.
U.S. Pat. No. 7,566,137 discloses an illumination maintenance system for maintaining a desired illumination profile in a building space, where the building space is illuminable by both daylight and electric light. The system comprises a sensor for sensing an illumination level of the space, a plurality of dimmable electric lamps to supplement the illumination of the space and a control system for controlling the dimming levels of the electric lamps. The control system adjusts the dimming level towards a preset that will result in a desired illumination profile in the space. Embodiments are disclosed which further implements controllable window treatment for selectively altering the amount of daylight entering the space.
There is nevertheless still a need in the art for improvements.